start with using correct focal length lens
pay attention on the suitable wardrobe,
than carefully mold your subject with lighting,
follow by the pose to enhance body part yous want to show or hide the parts you don't want show,
plus use of props creativity,
that should help
but if done everything and still failed,
Can try the following
1. Ask model to stabd facing you
2. Ask model to put both hands on waist.
3. Ask model to twist waist to abt 45degrees
4. Then you move to face model's face
5. Take photo of model
In the old days, Portraits are almost always taken in a studio where lighting are well controlled and picture taken on large format sheet films and in Black & White. Generally a portrait would take a couple of weeks to be ready for viewing as after developing the film, the photographer would place these films (negatives) on a small light table and go about slowly to touch up these negatives one at a time. Since the negatives are in B&W, it's easier for him to touch up as he is only playing with one colour. Just shades of black. He can always trim off any unwanted areas with this method. Those days, a good touch up photographers can really get very good business. My uncle used to own such a studio and I used to, as a little boy watched him work in the darken room with his little brushes and black ink plus a little very sharp pointed blade which he used to remove some of the black masking on specific areas of the negatives. That was Art at work. Photoshop makes such work much, much easier for those who master the software.